The three-piece band lost to teenager Hannah Barrett in the final sing-off, when they performed Don't You Worry Child by Swedish House Mafia.
Their rendition of the tune – their best performance yet according to Nicole Scherzinger – wasn't enough to keep them in the popular talent contest.
Sharon Osbourne was the judge to seal their fate: "It was the best sing-off, this is how everybody should be every single week.
"I'm sorry, I have to send home Miss Dynamix," she said.
Gary Barlow, the trio's mentor, backed them in their final battle on the show. Nicole, meanwhile, chose to back her own act, soulful singer Hannah – despite thinking the band had just performed their best so far.
Nicole told Miss Dynamix: "That was the best I ever heard you.
"I'm so proud of you, but obviously I'm going to go for my baby girl."
Miss Dynamix came bottom in the viewers' Flash Vote on Saturday night after singing Gabrielle's Dreams.
Hannah, who received the fewest votes out of the remaining contestants, broke down in tears as she finished her take on Emeli Sande's hit Read All About It.
When Louis Walsh was asked who he would have sent home he only said: "For me Hannah Barrett is world class, I would have gone for her."
Earlier in the programme, boy-band The Wanted took to the stage to show the contestants how it's really done.
But US pop star Lady Gaga stole the show wearing a blonde wig and dressed in nude-coloured lingerie. Surrounded by a troupe of scantily clad dancers, she strummed the opening chords of promotional single Venus on an acoustic guitar.